1. Field of the Invention
This invention relates generally to high pressure fluid pumping systems, and more particularly to a high pressure fluid pumping transformer and method for raising the pressure of a working fluid.
2. Brief Description of the Prior Art
Problems related to the fatigue failure of components are the limiting factor in current high pressure pump design. Reciprocating seals also pose problems due to wear but their replacement is typically simple and inexpensive relative to replacing metal components that fail from fatigue damage.
Heretofore fluid transformers, intensifiers and pumping systems, such as disclosed in U.S. Pat. Nos. 3,809,502 to Henry, 3,811,795 to Olsen, and 4,844,700 to Henderson, were not capable of operation continuously at pressures above that which caused stresses in its components greater than their fatigue life. The resulting extensive propagation of deep fractures into the body of components is obviously unacceptable.
Attempts have been made to solve the fatigue problem by supplying liquid tight chambers subject to internal pressure fluctuations and connecting this jacket to the discharge line of the pumping device. Typical high pressure pumps have a plurality of chambers into which a plunger reciprocates. Check valves are fitted in the chambers allowing flow into the chamber from a relatively low pressure source and out from the chamber into a relatively high pressure discharge conduit. All pumping chambers in the pump unit are connected to the discharge conduit and their relative progress through the reciprocating cycle is staggered so as to supply a relatively constant discharge flow to the discharge conduit. By surrounding the chamber with a jacket containing a relatively high pressure, the chamber stays in a state of compressive stress throughout its pumping cycle. This continuous output discharge pressure is limited by the fatigue life of the chamber and valve components. The chamber experiences pressure fluctuations from the inlet flow pressure to the discharge pressure. Other designs, such as disclosed in U.S. Pat. Nos. 3,370,545 to Waibel, 3,490,344 to Archer, 3,778,196 to Vereschagin et al, and 3,508,849 to Weber, have surrounded the suction/discharge valve assembly with a jacketed fluid at the discharge pressure to reduce their fatigue failure. These designs are limited by the compressive stress fatigue life of the valve components.
The present invention is distinguished over the prior art in general, and these patents in particular by a high pressure fluid pumping transformer apparatus which has a cylindrical transformer body surrounded by an outer pressure sleeve defining an annular working fluid chamber substantially surrounding the transformer body which receives fluid from an external source. The interior of the transformer body is divided into a central exhaust chamber and axially spaced working chambers at each end thereof. High pressure cylinders mounted in the transformer body at the end of each working chamber have a high pressure chamber spaced axially outward of the working chambers which contains a suction valve. Discharge valves mounted in the outer ends of the transformer body each contain a discharge valve and discharge port. An exhaust outlet extends from the exhaust chamber and is isolated from the working fluid chamber. A plunger reciprocally mounted in the transformer body has a portion which reciprocates in the working chambers and a reduced diameter at each end which reciprocates in the high pressure chambers. A shuttle valve slidably mounted on the transformer body moves in cooperation with the plunger to alternately open and close communication between the working fluid chambers. The working fluid pressure is used to compress all the internal components subject to internal fluid pressure fluctuations with a static pressure and at the same time supply the working fluid to the internal high pressure chambers to operate the plunger and also facilitates removal of heat from the seals and backup rings through which the plunger slides.